An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header, which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves and performs a threshing operation on the crop to remove the grain. Once the grain is threshed it falls through perforations in the concaves onto a grain pan. From the grain pan the grain is cleaned using a cleaning system, and is then transported to a grain tank onboard the combine. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material such as straw from the threshing section proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain into the vehicle.
More particularly, a rotary threshing or separating system includes one or more rotors which can extend axially (front to rear) or transversely within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves are transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to a cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself.
A cleaning system further separates the grain from non-grain crop material, and typically includes a fan directing an airflow stream upwardly and rearwardly through vertically arranged sieves which oscillate in a fore and aft manner. The airflow stream lifts and carries the lighter non-grain crop material towards the rear end of the combine for discharge to the field. Clean grain, being heavier, and larger pieces of non-grain crop material, which are not carried away by the airflow stream, fall onto a surface of an upper sieve (also known as a chaffer sieve) where some or all of the clean grain passes through to a lower sieve (also known as a cleaning sieve). Grain and non-grain crop material remaining on the upper and lower sieves are physically separated by the reciprocating action of the sieves as the material moves rearwardly. Any grain and/or non-grain crop material remaining on the top surface of the upper sieve are discharged at the rear of the combine. Grain falling through the lower sieve lands on a bottom pan of the cleaning system, where it is conveyed forwardly toward a clean grain auger.
The clean grain auger conveys the grain to a grain tank for temporary storage. The grain accumulates to the point where the grain tank is full and is discharged to an adjacent vehicle such as a semi trailer, gravity box, straight truck or the like by an unloading system on the combine that is actuated to transfer grain into the vehicle.
The cutter bar of the header typically includes a reciprocating blade moving atop a bar on which there are mounted fingers with stationary guard plates. The reciprocating blade operates in a channel on the bar and has very sharp sickle sections (triangular blades). The reciprocating blade is driven back and forth along the channel. The plant matter, is cut between the sharp edges of the sickle sections and the finger guard plates.
In DE 203 01 750 (Koeppl) there is disclosed a bar mower, having cutting devices that are divided into halves (FIGS. 1-8) where the mowing bar works with a serrated upper and lower blade, the upper blade being a divided upper blade (2), whose halves (2a, 2b) are simultaneously moved to the sides and back in order to cut the grass. A pulling and a pushing rod are joined to two twin armed levers connected to a linear drive with their opposite ends, moving the blades (2a, 2b) as shown in FIG. 6 of Koeppl. In FIG. 7 of Koeppl there is shown a stationary upper blade and movable lower blades 1a and 1b. In FIG. 8 of Koppl there is illustrated split upper and lower blades all of which are movable. A problem with split blades of this type is that there is a space between the blades in which the stationary blade alone meets some of the crop material, or even if all of the blades are movable there is no shearing action in the place where there is just one of the blades encountering the crop material.
What is needed in the art is a cost effective and efficient way of using a split blade system without having a portion of the crop encountering a blade that has no cutting/shearing action.